The effect of Muhlenbergia macroura dietary level on intake, digestibility and weight changes in volcano rabbit (Romerolagus diazi)

Abstract

The objective of the study was to evaluate the effect of different levels of Muhlenbergia macroura on feed intake, nutrient digestibility and daily weight changes in volcano rabbits. Thirty-nine-month-old mixed sex rabbits (n=32) were randomly allocated to four dietary levels of M. macroura, i.e. 0, 10, 20 and 30%. Following 14 days of adaptation, daily feed intake (DFI) and daily weight gain (DWG) were recorded and faeces collected during a one-day digestibility trial. Digestibility was estimated with lignin as an internal marker from the feed/faeces ratio. There was no effect (P>0.05) of treatment on DFI. As a daily average, rabbits consumed 26.2 g (SEM 0.20). There were linear (P<0.05) and quadratic (P<0.008) effects between grass levels and DWG. Weights were negatively affected as grass dietary levels increased. Mean DWG values were +1.5,−1.0,−2.1,−0.5 g/day for 0, 10, 20 and 30%, respectively (SEM 0.14). There was a quadratic response on digestibility of dry matter (DM) (P<0.04) and neutral detergent fibre (NDF) (P<0.02). Digestibility of DM for grass levels was 59.9, 67.6, 64.5, 62.3% (SEM 1.14) whereas digestibility mean values for NDF were 26.2, 39.3, 33.6 and 24.6%, respectively (SEM 2.26). Digestibility for organic matter, crude protein, ether extract, acid detergent fibre, ash and digestible energy was not affected (P>0.05) by grass levels. Daily requirement of digestible energy for maintenance in volcano rabbits was estimated at 178.1 kcal/kg WB0.75. Increasing dietary levels of M. macroura impairs DWG, even when DM and NDF digestibility showed a quadratic increase response.